Building on results suggesting that intraindividual variability in reaction time (inconsistency) is highly sensitive to even subtle changes in cognitive ability, this study addressed the capacity of inconsistency to predict change in cognitive status (i.e., cognitive impairment, no dementia [CIND] classification) and attrition 5 years later. Two hundred twelve community-dwelling older adults, initially aged 64-92 years, remained in the study after 5 years. Inconsistency was calculated from baseline reaction time performance. Participants were assigned to groups on the basis of their fluctuations in CIND classification over time. Logistic and Cox regressions were used. Baseline inconsistency significantly distinguished among those who remained or transitioned into CIND over the 5 years and those who were consistently intact (e.g., stable intact vs. stable CIND, Wald (1) = 7.91, p < .01, Exp(β) = 1.49). Average level of inconsistency over time was also predictive of study attrition, for example, Wald (1) = 11.31, p < .01, Exp(β) = 1.24. For both outcomes, greater inconsistency was associated with a greater likelihood of being in a maladaptive group 5 years later. Variability based on moderately cognitively challenging tasks appeared to be particularly sensitive to longitudinal changes in cognitive ability. Mean rate of responding was a comparable predictor of change in most instances, but individuals were at greater relative risk of being in a maladaptive outcome group if they were more inconsistent rather than if they were slower in responding. Implications for the potential utility of intraindividual variability in reaction time as an early marker of cognitive decline are discussed.

The ‘use it or lose it’ hypothesis of cognitive aging predicts that engagement in intellectual, social, and physical activities offers protective benefits from age-related cognitive decline and lowers dementia risk. Although this hypothesis has not yet been supported conclusively, there is some empirical evidence in favor of the proposal. However, a number of questions surrounding the relationship between activity participation and cognitive ability in older adulthood are not yet well answered. This mini-review identifies seven key methodological and theoretical issues that are critical to our understanding and eventual possible promotion of activity participation as a way to maintain cognitive well-being. These include the mechanisms involved, the optimal ways of assessing activity engagement, which cognitive domains receive the most benefit from activity engagement, the temporal nature and the directionality of the relationship, the influence of demographic variables such as age, gender, or education, and whether one activity domain offers the most benefit to cognition. The current knowledge on each of these issues is critically evaluated, including describing what we already know about the issue, and identifying potential difficulties and opportunities that may exist in finding an answer. More studies need to take on the challenge of specifically targeting these issues, as each is essential to moving the field forward.

Moment-to-moment intraindividual variability (IIV) in cognitive speed is a sensitive behavioral indicator of the integrity of the aging brain and brain damage, but little information is known about how IIV changes from being relatively low in young adulthood to substantially higher in older adulthood. We evaluated possible age group, sex, and task differences in IIV across adulthood using a large, neurologically normal, population-based sample evaluated thrice over 8 years. Multilevel modeling controlling for education, diabetes, hypertension, and anxiety and depressive symptoms showed expected age group differences in baseline IIV across the adult lifespan. Increase in IIV was not found until older adulthood on simple tasks but was apparent even in the 40s on a more complex task. Females were more variable than males but only at baseline. IIV in cognitive speed is a fundamental behavioral characteristic associated with growing older, even among healthy adults.

In this study, the authors addressed the longitudinal nature of intraindividual variability over 3 years. A sample of 304 community-dwelling older adults, initially between the ages of 64 and 92 years, completed 4 waves of annual testing on a battery of accuracy- and latency-based tests covering a wide range of cognitive complexity. Increases in response-time inconsistency on moderately and highly complex tasks were associated with increasing age, but there were significant individual differences in change across the entire sample. The time-varying covariation between cognition and inconsistency was significant across the 1-year intervals and remained stable across both time and age. On occasions when intraindividual variability was high, participants' cognitive performance was correspondingly low. The strength of the coupling relationship was greater for more fluid cognitive domains such as memory, reasoning, and processing speed than for more crystallized domains such as verbal ability. Variability based on moderately and highly complex tasks provided the strongest prediction. These results suggest that intraindividual variability is highly sensitive to even subtle changes in cognitive ability.

Objectives: Retirement is a major life transition in the second half of life, and it can be associated with changes in leisure activity engagement. Although theories of retirement adjustment have emphasized the need to find meaningful activities in retirement, little is known about the nature of changes in leisure activity during the retirement transition and their association with mental health. Methods: Based on four annual waves of the ‘Health, Aging and Retirement Transitions in Sweden’ study, we investigated the longitudinal association of leisure activity engagement and depressive symptoms using bivariate dual change score models. We distinguished intellectual, social, and physical activity engagement. Results: We found increases in all three domains of activity engagement after retirement. Although level and change of activity and depressive symptoms were negatively associated, the coupling parameters were not significant, thus the direction of effects remains unclear. Conclusion: The results highlight the need to consider the role of lifestyle changes for retirement adjustment and mental health.

The individualized nature of the aging process underlines the need to have neuropsychological tests that are sensitive enough to distinguish normal changes associated with aging from those that are pathological. However, these measures are only useful if adequate normative data are available. Normative data are presented for two new executive functioning tasks, the Hayling and Brixton tests, which were administered as part of a neuropsychological battery to 457 typically aging older adults (53-90 years). Advancing age was associated with poorer performance on both the Hayling and Brixton tests. Results showed that fluid intelligence accounts for some but not all of the age-related variance on these tasks.